Don't be fooled by the Penguin demo videos and I rarely buy on the strength of their videos alone. Some can look good but when they arrive, you will know that you just won't use it in your routine.
Places like magic box are also real shops whereas Penguin are a warehouse. You can pick up the phone and at magic box you can speak to a real live person

(I've heard that you're more likely to pass away whilst waiting for Penguin to answer the phone

)
You'll find that shops generally only take in the tricks that have a much better chance of selling as they can't afford to have too much stock hanging around and they have to sell over the counter as well as by post. In most cases I'll try to visit a shop and pay a bit extra having seen the demo in the flesh. I accept that this is not always possible for everyone but there you go.

Member of the Magic Circle & The 2009 British Isles Close-Up Magician of the Year
It's not really an optical illusion - it just looks like one!